I would like to apologize in advance for the terrible English you are about to read right now.

Right, so am currently experiencing an issue with several games regarding the SLI GPU usage of my GTX 680s, (more precisely BF4, GTA 5, Metro last light). I’m using EVGA Precision X to monitor the data (also used MSI Afterburner to see if there was a bug in the first mentioned software).

The monitoring softwares tell me that the usage rarely surpasses 65% in each car, which is kind of annoying considering that I would like to obtain as much power as I can from my video cards.

Here is a list of all the things that I’ve already try, making it easier for you guys to help me out:
- Clean install of drivers (GPU / Motherboard)
- System update for all relevant components and software.
- Set high priority power (maximum performance) in the NVidia control panel
- overclocked CPU up to 4.5GHZ (stable)
- Check temperatures and Fan speeds
- Registry clean up, and CC clean up.
- play with the in game graphic settings (the usage barely varies, even in low settings)
- Utilize Precision X's K-Boost (didnt even worked)
- Remove the video cards, and put them back again (in different order)
- Check the SLI cable for visible damage
- I tried lowering textures due to limited Vram but that was not the issue
- Run Unigine Heavens benchmark and compare to previous result. * Strangely during this benchmark my GPU usage is very good (around 90-95% both cards)
- I can ramp up the usage a bit by turning resulution scaling up, but thats not an "ideal" solution since it also affects the FPS
- went back to the previous driver version (still have the issue)
- Vsinc is off (in game and in Nvidia Control)

I really don’t know what else to do, and honestly I think I didn’t had this problem with BF4 a while ago (not sure though since I don’t remember very well what the GPU usage was a month ago)

I would really appreciate any help you can provide :)
 
EDIT: I’ve been using a Monitoring software for the past year and it is now that the GPU usage caught my attention, meaning that i don’t think I had the problem before.

Specs:

3770k OC 4.5 GHZ ATM (Stable)
2x EVGA GTX 680 2GB SLI 
2x 8gb HyperX Ram
850w cooler master power supply 
1TB barracuda HD
120gb SSD (boot drive only)
MSI z77 military class III motherboard
 
 

http://forums.evga.com/GTX-970-Low-GPU-usage-m2243734.aspx
 
Re-install windows.

Yeah I was expecting to do that sooner or later, was hoping for some light of hope that may add to the solution though, without having to go through a complete reinstallation.

digideath
I have ALMOST an identical setup to the op. I had an issue very much like this and fixed it without having to reinstall windows. Same with the other linked thread.

You all missed something pretty obvious...

Check yer pci express speeds on both cards. They should both be 8x. If one is 2x/4x and the other is 8x then post back and ill tell you how to fix :)

I doubt this is the issue. SLI requires both cards to be running at least x8 before you can SLI.

Sajin

digideath
I have ALMOST an identical setup to the op. I had an issue very much like this and fixed it without having to reinstall windows. Same with the other linked thread.

You all missed something pretty obvious...

Check yer pci express speeds on both cards. They should both be 8x. If one is 2x/4x and the other is 8x then post back and ill tell you how to fix :)

I doubt this is the issue. SLI requires both cards to be running at least x8 before you can SLI.

Wrong. EXACTLY that happened to me with both my cards just last year. Gpuid showed one at 2x and the other at 8x. It took me a while to figure out why it was bottlenecking and that's exactly what was causing it. It was down to a borked NVidia driver installation that badly bugged windows out. Windows literally locks at that from then on no matter how many times you reinstall drivers. I found a way to fix it but.

Edit: For example. You do know there are tools out there. Dirty hacks that allow you to place one card in a 16x standard pci e slot and one in a 4x slot to gain sli on a non sli board? One card runs at 8x the other at 2x yet they still sli together. Google "hypersli". It is definatly possible for the cards to still sli without pci e speeds matching.

Yeah but then how do explain the fact that in my own system just last year, on a fully compatible sli motherboard, one card locked at 2x the other at 8x yet sli was still enabled and functional using a standard NVidia driver?

Yep and that's exactly what im saying to the op. Im suggesting he has the same issue. And to correct you there. Not video driver corruption. A windows bug. It may have been triggered by a driver installation just a couple of days before BUT the bug happens in windows itself. That's why no matter how many times you do a clean install afterword's, it wont fix it. You have to address the issue in windows itself. Its also what bottlenecks the gfx because, as you should know, you're only as fast as yer slowest card and at 2x being the lowest, there's no way the bandwidth provided can keep up with the true speed of the cards.

Also to further add. It's not just corruption or bugs that cause it. The drivers literally can do that without hacks or bugs, intentionally. Read here. This review demonstrates the losses and gains of dropping your card down a slot into a lower speed pcie slot and it clearly demonstrates a standard NVidia driver locking the cards at different speeds. People do this for many reasons. The main one being better airflow in the system. Its a little dated but I can find you a more up to date demonstration if I spend longer looking.

http://www.hardocp.com/article/2010/08/16/sli_cfx_pcie_bandwidth_perf_x16x16_vs_x16x8#.VT_5c1hFCUk

Sajin
So how do you fix it then?

That's actually very easy :)

First you need to understand that the bug happens in a section of windows known as the "device mapping table". Corrupt values get locked in there and remain permanent till you physically either force it to rebuild itself or by changing hardware.

Easiest way to do it?
Full clean uninstall of drivers to start with.
Enter safe mode and delete the device/devices.
Swap out cards if you have a spare. If not. If sli then pull one card. Install the other in a slot you haven't used before. If one card, just swap slots.
Boot windows.
Clean install drivers.
Clean uninstall drivers.
Delete all gfx devices in safe mode again.
Put yer config back to the way you had it before.
Clean install of drivers.

That should be it. Fixed. That's what fixed it for me. Much easier than reinstalling windows.

Both Cards say X8. ill post some gpu-z pics
 
       
 

Here is how I set my two cards in SLI Mode.
 Note the GPU Clock Offset setting for each card.
You can click on image for a larger view.

digideath

Sajin
So how do you fix it then?

That's actually very easy :)

First you need to understand that the bug happens in a section of windows known as the "device mapping table". Corrupt values get locked in there and remain permanent till you physically either force it to rebuild itself or by changing hardware.

Easiest way to do it?
Full clean uninstall of drivers to start with.
Enter safe mode and delete the device/devices.
Swap out cards if you have a spare. If not. If sli then pull one card. Install the other in a slot you haven't used before. If one card, just swap slots.
Boot windows.
Clean install drivers.
Clean uninstall drivers.
Delete all gfx devices in safe mode again.
Put yer config back to the way you had it before.
Clean install of drivers.

That should be it. Fixed. That's what fixed it for me. Much easier than reinstalling windows.

if you like wasting a lot of time to solve a simple problem then yes go for this idea.